The present invention relates generally to a methods for the insertion of an intraocular lens into an eye. More specifically, the invention is directed to the insertion of a lens into the capsular bag after the natural lens has been removed, for example because of the presence of a cataract. The invention also relates to the resulting arrangement and a packaging for use therein.
The insertion of artificial lenses into patients is a process familiar to ophthalmic surgeons. Cataract removal may be intracapsular or extracapsular. Intracapsular cataract extraction includes complete removal of the lens, the capsular bag enveloping the lens, and the zonules connecting the capsular bag to the scleral wall of the eye. Extracapsular cataract extraction is performed to remove the cataractous lens while leaving the capsular bag and zonules intact within the posterior chamber of the eye. In this procedure, a capsulorhexis incision is performed to remove a generally circular mid-portion of the anterior capsule of the capsular bag, thereby leaving the posterior capsule, an annular anterior capsular flap and a generally circular anterior capsulorhexis edge. The cataractous lens is removed from the residual capsular bag and replaced with an artificial IOL. The IOL has haptics to engage an inner peripheral surface of the residual capsular bag and centralize the IOL within the capsular bag. The present invention is related to replacement lens insertion following extracapsular lens removal.
IOLs may be subdivided into two types. A first type is referred to by the term plate haptic lens, described for example in U.S. Pat. No. 5,919,230 incorporated herein by reference for all purposes. These plate haptic lenses may be hard and non-foldable or soft and foldable. Soft lenses are preferred because they may be inserted through a smaller incision.
A second type of IOL is referred to by the term xe2x80x9cJxe2x80x9d or xe2x80x9cCxe2x80x9d haptic foldable lenses which have two or more generally J- or C-shaped legs extending from a central lens, described for example in U.S. Pat. No. 4,542,540 and PCT Application No. PCT/JP98/05370 (WO99/27978 and European Patent Application EP 0 968 727 A1) both incorporated herein by reference for all purposes.
A known problem of soft plate haptic lenses in particular is their tendency, once implanted, to be affected by capsular shrinkage. Because the materials used are relatively soft they do not resist such a shrinkage of the capsular bag. Plate haptic lenses can also suffer from decentration accompanied by capsular shrinkage and spontaneous luxation after YAG laser treatment.
There is a desire to be able to replace the natural lens with a lens which provides a correction of astigmatism. Such a lens is available from the Staar Surgical Company, Monrovia, Calif. in the form of a toric foldable plate haptic lens. Because of the astigmatism correction, it is particularly important that such lenses do not rotate after insertion. In order to reduce the occurrence of lens rotation, the manufacturers provide fenstrations in the haptics to allow fibrous lens epithelial cells to grow through and provide a securing mechanism.
Another IOL which is designed to correct for astigmatism is described in U.S. Pat. No. 5,824,074 and comprises two IOLs which can be rotated with respect to each other to provide the necessary correction. This design has a particular requirement for preventing subsequent rotation of the lenses.
Solutions for preventing the rotation of inserted IOLs have been proposed. As indicated above, the plate haptic IOLs from the Staar Surgical Co. include fenestrations to promote fixation through the growth of cells. Other concepts include suturing, as described in European Patent Application EP 0 884 030 A2, in which a xe2x80x9cCxe2x80x9d haptic foldable lens incorporates loops on the locating legs which are attached by a transscleral suture. A disadvantage with the former solution is that a certain period of time is required for the cells to grow through the fenestration and secure the lens and a disadvantage of the latter is that the suturing is a further invasive procedure.
There exists a need for improved methods and materials for the insertion of an intraocular lens.
It is an object of the present invention to provide a means for securely locating an intraocular lens in position. The present invention provides a method for inserting an intraocular lens into an eye comprising the steps of removing an existing lens so as to leave a capsular bag intact; at least partially inserting an intraocular lens having at least one haptic incorporating an aperture therein into the capsular bag; and inserting a capsular tension ring into the capsular bag such that the capsular tension ring passes through the aperture.
Preferably, the lens to be inserted is a toric lens which may correct for astigmatism in the treated eye. Such a toric lens may be a plate haptic lens or otherwise. The capsular tension ring may be adapted to self-locate itself relative to the intraocular lens by means of a loop in its shape.
The invention further provides an intraocular lens arrangement comprising an optical lens having at least one haptic attached thereto, the haptic having an aperture therein and a capsular tension ring threaded through the aperture.
In a still further aspect of the invention, there is provided a sterile package of items comprising a replacement intraocular lens having at least one haptic, the at least one haptic having an aperture therein; and a capsular tension ring.
The methods and apparatus described herein may generally be used in animals, preferably in mammals such as humans, cats, and dogs, and more preferably in humans.
A further understanding of the nature and advantages of the inventions herein may be realized by reference to the following description of embodiments of the invention with reference to the attached drawings.